@Kaido:
There will be plenty of time in this arc that will be devoted to Kaido, and Big Mom, and the impact they have on the world.
Sometime at the end of Wano or just after it there will be some chapters of transition that should set the context of the next SH journey and they will most likely consist of what WGℑ, Blackbeard, Revo's and Shanks are doing. Wano was set up long ago, but after this, there isn't any planed adventure or trail that the SH's know about (only if they read KAidou's Poneglyph and discover some new route).
The Elbaf arc is a possibility but by that time i think part of the characters i mentioned will have a more proeminent role in the story- thus Oda needs to show what they are up to before that so we can understand the plot at the very least.
Anyway, that is how i see the story unveil by the time we are finished with Wano. There aren't too many places the SH"s can go after this (except Elbaf& Raftel ofc) that has been hyped/discussed/hinted in the past.